1. Field of the Invention
The present invention relates to the production of caseinate-based seafood analogs. More particularly, the invention is directed to formulations and processes for producing non-textured kamaboko analogs; or with texturization, imitation products of crab, shrimp or lobster.
2. Description of the Prior Art
Seafood analogs represent a rapidly growing market segment of the food industry. Surimi, a minced fish product produced primarily from Alaska Pollock, has the unique textural and functional properties requisite for these analogs. Kamaboko, frequently referred to as steamed fishcake, is a typical Japanese seafood which has its origins in the tenth century where it was developed as a means of preserving the gelling properties of washed, minced fish. While many fish species have in the past been used for its production, the primary source in the domestic production of kamaboko today is Alaska Pollock, due to both its ready availability and acceptable gelling properties.
Kamaboko is a homogenous protein gel made from fish myoftbrilla protein. This product, which is primarily actomyosin, is produced by the removal of water soluble proteins through washing, solubilization of the actomyosin with sodium chloride, and heating. The Japanese term "ASHI" refers to the unique cohesive and highly elastic texture which is characteristic of kamaboko.
Milk proteins are highly desirable as ingredients in foods. In addition to their availability and high nutritive value, their utilities as food bases are enhanced by the bland products they provide. Casein, the major protein component of cow's milk, and its caseinate derivatives have physicochemical, functional and nutritive properties which make them useful for such purposes. Products containing high concentrations of caseinate have exceptional water-binding capacity, fat emulsification properties, whipping ability, and are viscous and soluble under neutral or alkaline conditions. These proteins are currently used in a variety of products, including coffee whiteners, cheese analogs and meat products.
The emphasis on the production of fabricated foods has increased the demand for highly purified food grade proteins, commonly referred to as functional proteins, of which milk proteins serve as one of the most important sources.
Milk proteins are known to gel when subjected to acid treatment, heat treatment, aging, or rennet treatment. Casein is the component involved in each of these gels. The most prominent example of the rennet-induced caseinate gels is in the manufacture of most cheese varieties. Gels have been obtained from calcium caseinate (CaCN) dispersions at concentrations greater than 15% when heated to 50.degree. C. to 60.degree. C. These gels, however, have the disadvantage of being reversible and liquefy slowly on cooling.
The utilization of caseins and caseinate for their properties of gelation has thus far been limited to their use as binding, thickening or emulsifying additives to some other food component. Prior uses for casein as a solid viscoelastic "stand alone" gel are primarily limited to cheeses and yogurts.
Gels have also been obtained from skim milk curd by the addition of CaCl.sub.2 with subsequent autoclaving. The resultant gels contained 30 to 40% solids primarily in the form of protein. These products were considered to have a structure that was too close and homogenous to simulate the structure of meat.
It is known that the structure of caseinate gels can be altered significantly with the use of polysaccharide additives. Inclusion of potato starch is known to be effective for increasing the rigidity of surimi gels; this being due to its high water absorption characteristics. Carrageenans have been used extensively in a wide range of food systems as thickening, suspending and gelling agents and are frequently added to dairy products, such as ice cream, custards or chocolate milk to improve viscosity. Moderately high concentrations of .kappa.-carrageenan cause casein to gel.
U.S. Pat. No. 4,209,534 discloses a method for producing a thermally stable textured milk protein product resembling beef. In the process, whole partially skim or skim milk is subjected to pasteurization at a temperature of 72.degree.-92.degree. C. for 15-30 seconds with the addition of one or more calcium salts. Five percent to 25% by volume of the milk to be processed is cooled to a temperature of 40.degree.-70.degree. C. and mixed with animal or vegetable fats and then homogenized. The homogenized mixture is then combined with the remaining portion of the milk, which can then be processed by the addition of acids such as phosphoric acid. A pulp is formed by enzymatic coagulation of the casein and milk albumins, disintegration and reducing the water content of the coagulate to 70%-80% by weight. Preliminary texturization of the granulated pulp is carried out by thermal plasticization at 60.degree.-80.degree. C. in an acidified aqueous solution. Principal texturization is done at 40.degree.-60.degree. C. by squeezing the pulp in a screw extruding press, disintegrating the obtained textured milk proteins into pieces of various sizes and conditioning these pieces at 14.degree.-20.degree. C. Subsequent freezing and lyophilization steps restore the finished textured milk protein. In this process, polyphosphate, carrageens and pectins can be added to the pulp after the preliminary texturing.
U.S. Pat. No. 3,996,390 discloses a system for the preparation of an acidified milk gel. The composition comprises a thickener system of carboxymethyl cellulose and gelatin.
U.S. Pat. No. 2,813,794 discloses a process for preparing a chewy casein gel for use in protein food products simulating meat. This process comprises forming an aqueous solution of casein at a pH of about 1.8 which is then heated to a temperature above 70.degree. C. whereupon a water-soluble calcium salt is added thereto to give a calcium ion concentration of about 0.1 normal. The pH is then adjusted to 6, with the resultant gel precursor being collected and the gel is then being heated with saturated steam at 15 psi for 15 minutes.
U.S. Pat. No. 4,080,477 discloses the creation of a soy-containing cheese-like product by adding both a casein-containing substance derived from animal milk and an emulsifying salt to natural soy cheese and agitating the mixture under relative high sheer conditions. The process is carried out at an elevated temperature not exceeding 85.degree. C. for a period of time sufficient to form the mixture into a softened, full bulk consistency.
U.S. Pat. No. 4,883,683 discloses a method for the preparation of solid foodstuffs comprising reacting an alkaline earth metal-type solidifying agent with an aqueous emulsion comprising soybean protein, a casein, oils and fats. The mixing and emulsification of products produced lacked coarseness or dryness but have excellent melt in the mouth properties.
U.S. Pat. No. 4,250,198 discloses a meat snack analog made from non-meat protein material, fat, water, spices, coloring and flavoring. This material includes a protein binder such as sodium caseinate and powered egg white.
It is an object of the present invention to provide a formulation and process for the preparation of food analogs including seafood analogs from milk proteins. A further object of the present invention is to provide a method for the preparation of a milk-based protein product having the texture of a seafood analog such as imitation crab, shrimp or lobster.